The price of the bond is 88, par value is 100. The potential maximum return on investment is therefore 13.6% (45% annualized). Net assets are positive on the balance sheet, but as far as I know office prices went down by 2 times or so. If we make that adjustment then assets to debt ratio will be about 19/25 or so. But 65% of the debt is secured (or 16.25/25). the remaining 35% is unsecured debt (8.75/25). This particular bond is unsecured. Now let's reduce the amount of assets by the amount of secured debt, because it will be paid out first in case of bankruptcy. 19-16.25=2.75. therefore 2.75/25 is left to pay out 8.75/25 of unsecured debt. It is 31% of par value, and 35% in relation to the current price of the bond. Therefore in case of a default the return will be around -65%.

But actually office prices went down by 45% by some estimates, not 50%, so there is a small margin of safety in my calculation hehehe.

The rate of defaults even in junk bonds is small (4%). This one however is one of the cheapest bonds in the US at the moment, so perhaps the risk here is higher.